TL response of muscovite samples from granite pegmatite of Ilesa and Ijero-Ekiti, Southwestern Nigeria

Thermoluminescence of gamma-irradiated muscovite samples from two deposits in Southwestern Nigeria have been studied. Their glow curves and TL sensitivity are shown to be deposit dependent. TL peaks are observed around 238 and 330∘C in one, and only at 238∘C (as measured with a heating rate of 8∘Cs-1) in the other. The dose responses of the glow peaks have a super-linear behaviour at low doses followed by linearity and then become sub-linear at high doses. The TL sensitivity of the annealed samples was found to be lower than that of unannealed ones and a possible explanation is given. Fading studies show that over a period of one month, the TL signal from the irradiated sample remained relatively stable. Comparison of the results from the present work with those found in the literature showed that, though the TL properties may be deposit dependent, muscovite might possess some properties that are similar irrespective of deposit. These results further indicate the potential of muscovite as a phosphor in retrospective dosimetry and TL dating.